El RS4 y R8 en el dyno

[Nautiliux]

www.automobilemag.com

 

There can be no doubt that Audi is making two of the very hottest vehicles in the world. So hot are these cars, that I don't even need to mention names. Which we still find odd, as Germany's other luxury automobile has long been the official car of architects, graphic designers and therapists, not tail-out, tire-smoking hoons. But the cars speak for themselves. Or rather, the lustful, sinful, Pope-angering 4.2-liter FSI V8 they share speaks for them.

 

The RS4 is a true giant killer, stealing the formula first developed for the E39 M5 and improving upon it in every way. And of course the R8 is the new girl who transfers into the 11th grade, upsetting and turning the hot chick pecking order on its head (we still reserve the right to think it's funny looking). But in each car, it is the engine and the engine alone that elevates these cars into the stratosphere. Automobile Magazine placed both of them on a dynometer and we couldn't be less surprised by the results.

 

The dry-sumped, smaller flywheel R8 revs a bit quicker and puts down 7 more horsepower (338 hp vs. 331in the RS4) at the wheels. However, the "when I grow up I wanna be a freight train" RS4 makes a little more torque a whole lot lower down in the revs: 276 lbs. ft. @ 3,750 rpm for the 4-door, 275 lbs. ft. @ 5100 for the dolphin head coupe. – Jonny Lieberman.

 

 

Dyno Test:

 

By Jason Cammisa

 

 

 

Our Four Seasons Audi RS4 has a lot of fans around the office. While it's a great all-around car, it's the 8,250-rpm, 420-hp, 4.2-liter engine that really gets our attention. The V-8's power delivery is so linear that it feels like an electric motor, except of course no electric motor could ever sound this good. I once described its staccato exhaust note as sounding like a thunder cloud. Assistant editor Sam Smith said it sounded "like an angry, drunken bear being shot from a cannon." One of us is obviously a big fan of hallucinogenics.

 

Anyway, Audi's new R8 shares the RS4's engine, albeit with a couple of small changes. First, it has different intake and exhaust paths due to its mid-engine layout. Then, its dry-sump lubrication system allows the engine to be mounted lower in the chassis, permitting the use of a smaller, and lighter, flywheel.

 

The lightened flywheel is evident as soon as you turn the key. The R8's V-8 revs much more quickly than the RS4's. So quickly, in fact, that it seems the flywheel must be made of helium. Teensy little prods of the throttle result in huge surges of revs, with sharp barks of anger shooting out of the short exhaust pipes.

 

 

In gear under load, the R8 sounds frenetic, evil, and pissed off. By comparison, the RS4 sounds happy, refined, and non-threatening. Never thought you'd hear those words about an RS4, did you? The R8 sounds that good.

 

On the road, the R8's power delivery felt similar to the RS4's - it has a huge amount of torque available at any speed. Unlike the RS4, though, which hits hard at 3000 rpm and stays there, the R8's torque output builds with revs, gradually coming to its peak.

 

This isn't surprising - the RS4 uses long intake runners, which help boost low-end torque, while the R8 uses short runners that favor high-rpm breathing. That small difference was enough to convince me to take both cars to a chassis dyno to find out how much of a difference there really is.

 

We had to massage the final chart because the R8 exhibited a big drop in output between 2000 and 4000 rpm on the fourth gear runs, caused by a glitch in the European-specification, pre-production powertrain computer. The curves shown below are corrected using the fifth gear curves as a guide. The dyno used was a Dynapack 5000, which typically reads a little lower than the more common DynoJet unit.

 

Since everyone asks about peak numbers first, the RS4 put down 331 hp to the wheels, the R8 put down 338. The difference between those two numbers, which is about two percent, is insignificant. Given the 420-hp rating at the engine, their output corresponds to twenty percent drivetrain loss, which is commendable for an all-wheel drive setup.

 

The dyno chart confirms what we felt in the seat of our pants - the RS4 has a bigger torque plateau in the mid-range, where the R8's torque curve rises more slowly. Both engines, however, have torque curves so robust that they would have been unimaginable only a few years ago.

 

And both sound incredible.

 

 

Editado 23 de Junio del 2007 por Nautiliux

[Nautiliux]

 

 

[grp]

Hola...el problema radica que los nuestros dan unos 188 kw a la rueda...es decir...255 CVS.....que con la correccion de perdida...nos dan unos 358 CVs reales Norma ISO

 

Lo que vamos diciendo...que faltan unos 70 cv...tanto a la rueda como en Norma ISO...

 

Un saludo

 

GRP

[daniS-Line]

A mi con el diseño "gláctico" del R8 ya me sobraroia, aunque el que pague por el 120000 lereles no le haria mucha gracia...

 

Aunque la gracia de este coche es la posicion del motor y el comportamiento...bueno son suposiciones porque no lo he probado..ya me gustaría, incluso con menos potencia

[Terrazza]

encuentro que audi se ha arriesgado mucho montando el mismo bloque en el R8 que el Rs4,con tanta especulación sobre éste...

realmente no sé si da más o menos cv,pero es un trueno de motor...

en fin mi nota al R8 con combinación blanco-carbono con las 19" es un 8,5... me sobras las "branquias" traseras, las encuentro demasiado exageradas... pero bueno, me lo quedo

[frpra]

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